| More complex modulation schemes are adopted in the modern wireless communication system in order to improve the spectrum efficiency.This technique also increases the peak-to-average power ratio of the signal and causes low efficiency of power amplifier.To increase efficiency,the envelope tracking power amplifier,envelope elimination and restoration and other techniques have been proposed in the literature.That's to say,it's significantly meaningful to design high efficiency linear power amplifier for handset devices.A hybrid envelope tracking power amplifier is refined and designed in this thesis.The envelope modulator is composed of linear amplifier,current sensing,bias controller,programmable hysteresis comparator,envelope shaping,and switch amplifier.The architecture uses shaping envelope as the input of envelope amplifier,and then the signal in the output of linear amplifier is fed back to envelope shaping by biasing circuit,which increases the output efficiency of envelope tracking power amplifier.The theoretical derivation of noise and loop characteristic are presented in the thesis.Lastly,a differential input linear power amplifier circuit is designed in the thesis,and the cascade structure is used to realize high output power.Input and output matching networks are designed with off-chip discrete components.In conclusion,hybrid envelope amplifier and power amplifier are combined in the thesis,so the improved output efficiency and power meet the application need.The schematic design and layout design of the high efficiency power amplifier and the verification of the pre-simulation and post-simulation are all completed based on SMIC 0.18?m CMOS process.The postsimulation results show that the high efficiency linear power amplifier achieves an average output power of 21.05 dBm,a power-added efficiency of 26.2% and a power gain of 22.1dB for 1.80 GHz input signal.The performance indicators meet the design targets. |
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